Environmental and occupational exposure to industrial dusts is causally linked to respiratory carcinogenesis and to chronic respiratory disease. These pollutants are deposited to a large extent in upper airways where they may be removed or trapped within the tracheobronchial secretions, producing an altered mucosa. Epidemiologic and experimental evidence suggests that intercurrent viral infection and exposure to cigarette smoke may act synergistically with these agents. In this project, we will explore the effects of 4 dusts (carbon, fiberglass, hematite, and asbestos) on human tracheobronchial mucosa in organ culture. Hamster tracheobronchial explants will be used as a model system for experimentation. After precipitation of known amounts of dusts onto cultures of respiratory epithelium, aspects of cellular metabolism and the composition of mucin secretions will be assessed biochemically and correlated with morphological light and electron microscopic observations. This study is designed to elucidate the cellular changes occurring consequent to particulate impingement upon the respiratory epithelium. Such information may be indicative of epithelial responses in the early stages of carcinogenesis or chronic respiratory disease.